Microfluidic systems for analytical and diagnostic systems are also known, inter alia, as a “lab on chip” and are produced on glass or plastic substrates. The substrates in this case comprise channel or valve structures for fluids intended for analysis to be conducted through. Furthermore, active, micromechanical elements are arranged, such as for example pumps, etc., which are in operative connection with the channel or valve structures. The pumps serve, for example, for transporting or metering the fluid to which the channels are subjected.
For reasons of simplicity, microfluidic systems of this type are mainly produced using plastics technology, for example by means of injection molding or else by means of stamping or forming techniques. Furthermore, these microfluidic systems may also comprise structured metallic conductors and corresponding connections.
Microfluidic systems produced in this way are relatively inexpensive. However, the possible functions and application areas are restricted. For example, no optical analysis by means of CCD image sensors is possible. Furthermore, on account of the injection-molded plastics technique that is used, the production of the channel or valve structures is relatively inaccurate. The active, micromechanical elements, such as pumps or the like, are in this case produced from silicon and applied directly to corresponding openings of the channels, as are also corresponding electrical contacts for activating the active, micromechanical element on the substrate. The active, micromechanical elements are in this case arranged next to one another from above on the corresponding channels or the openings thereof and accordingly have in each case a channel gate or feed of their own. Furthermore, electrical contacts of an active, micromechanical element produced using silicon technology make complex and cost-intensive contacting methods necessary, since substrates of plastic and active, micromechanical elements of silicon have completely different tolerances and structural accuracies.
DE 602 14 167 T2 discloses a microfluidic system which comprises a number of layers stacked one above the other. Arranged in the respective layers are channels or chambers, which are produced by removing material over the entire thickness of the respective layer. This three-dimensional layer structure is used for the purpose of separating fluids.